A head-up display (HUD) is a computer-operated system that presents significant information or visual images to a user's focal view. The head-up display presents data on a transparent display, enhancing a driver's driving capability by fulfilling the requirements for safety, comfort, and information.
Head-up displays can use different types of displays. FIG. 1A illustrates an example of a head-up display 100, which uses a windscreen 102 of a vehicle for displaying information or visual images. FIG. 1B illustrates another example of a head-up display 150, in which a combiner display 152 is included to display information or visual images thereon. The combiner display 152 is usually an angled flat piece of glass located in front of the viewer.
A head-mounted display (HMD) is another type of head-up displays, and uses a display element moving with the orientation of the user's head.
When used for augmented reality applications, a head-up display may be referred to as an augmented reality (AR) HUD system which shows exterior view of traffic conditions in front of the vehicle with virtual information or augmented information for the driver. Augmented reality head-up displays thus incorporate augmented information as part of the driving experience.
However, current head-up displays present information or images with distortions. Head-up displays present the image relatively close to the driver, whereas the driver usually focuses his sight much further beyond the windscreen. This difference in eye focus and image angle causes distortion, and image may thus appear split as shown in image 200 of FIG. 2.
To reduce the image distortion, some approaches use mirror reflections in a projector unit of the head-up display to put the image “floating” beyond the windscreen. This mirror reflection approach could not completely eliminate the image distortion. At the same time, it will be difficult to place overlaying augmented information accurately on the objects on the road.